Apparatus for recovering a drill stem

ABSTRACT

A tool is disclosed for recovering a drill pipe embedded in the ground and detached from a drill string extending from the pipe to a point above ground. The tool has an upper and a lower body portion in axial alignment and a fluid chamber in the tool between the body portions. Each body portion has longitudinal cavities spaced radially about the axis of the body portions and communicate with the fluid chamber. The cavities are at acute angles to the axis of the tool the vertex of each angle being on the side of the cavity nearest the fluid chamber and each cavity having an opening at the end remote from the chamber which defines a groove along the body portion. A wedging member is positioned in each cavity and is slidable therein so that the shank of the wedging member projects laterally and outwardly from the body portion when fluid is passed into the cavities. The shank of each wedging member has a flat toothed portion from gripping the inner wall of a drill pipe. The tool is connected to the end of a drill rod and lowered down the upper drill string until the upper body portion is positioned in the upper drill string and the lower body portion is positioned in the detached drill pipe. Fluid is passed down the drill rod and into the longitudinal cavities whereby the wedging member is projected and grips the inner wall of the upper drill string and drill pipe. The drill rod upper drill string and drill pipe can then be raised from the ground.

United States Patent Sandquist [54] APPARATUS FOR RECOVERING A DRILLSTEM [72] Inventor: Alvin V. Sandquist, Calgary, Alberta,

Canada Becker Drills Limited, Calgary, Alberta, Canada [22] Filed: Feb.5, 1970 [21] Appl.No.: 8,866

[73] Assignee:

Primary Examiner-Harvey C. Hornsby Assistant ExaminerMerle F. MaffeiAttorney-William George l-lopley Feb. 1, 1972 [5 7] ABSTRACT A tool isdisclosed for recovering a drill pipe embedded in the ground anddetached from a drill string extending from the pipe to a point aboveground. The tool has an upper and a lower body portion in axialalignment and a fluid chamber in the tool between the body portions.Each body portion has longitudinal cavities spaced radially about theaxis of the body portions and communicate with the fluid chamber. Thecavities are at acute angles to the axis of the tool the vertex of eachangle being on the side of the cavity nearest the fluid chamber and eachcavity having an opening at the end remote from the chamber whichdefines a groove along the body portion. A wedging member is positionedin each cavity and is slidable therein so that the shank of the wedgingmember projects laterally and outwardly from the body portion when fluidis passed into the cavities. The shank of each wedging member has a flattoothed portion from gripping the inner wall of a drill pipe. The toolis connected to the end of a drill rod and lowered down the upper drillstring until the upper body portion is positioned in the upper drillstring and the lower body portion is positioned in the detached drillpipe. Fluid is passed down the drill rod and into the longitudinalcavities whereby the wedging member is projected and grips the innerwall of the upper drill string and drill pipe. The drill rod upper drillstring and drill pipe can then be raised from the ground.

4 Claims, 7 Drawing Figures PATENTED KB 1 m2 SHEET 1 OF 2 ALw/y v.smvpqul r l N VEN TOR.

, APPARATUS FOR RECOVERING A DRILL STEM portion of drill pipe which isembedded in the ground and broken or otherwise detached from a drillpipe immediately above it and extending above the ground.

The loss of a portion of a drill string in a hole involves considerablecost. In drilling operations in certain types of earth formations suchas overburden, breaks in the drill stems result in adding considerablyto the expense of drill operations. Because of this various attemptshave been made in the past to recover such drill stems. Apparatus forrecovering drill stem are sometimes known in the art as fishing tools."Such fishing tools have met with varying degrees of success.

, The method used for recovering drill stem with a fishing tool of theprior art required the removal of the portion of the drill string abovethe break. The fishing tool was then secured to the end of a drillstring and lowered into the hole. The drill string was lowered until thefishing tool was inserted into the inner annulus of the broken drillstem. Once inside the fishing tool was attached to the drill stem bymeans of slips on a tapered seat or by threads on the tapered point ofthe fishing too]. However, when the portion of the drill string abovethe break is removed from the hole, the earth formations or overburdenfrequently fall into the hole and closes the broken end of the drillstern. This not only makes the drill stem difficult to locate but theslips or thread of the fishing tool become dirty and cannot attachitself to grip the drill stem properly. This problem is avoided by theapplicants fishing tool by the nature of its construction and by reasonof the fact that the drill string above the break does not have to beremoved prior to lowering the applicants apparatus.

It is therefore an object of this invention to provide an improved toolfor recovering a drill stem.

It'is another object of this invention to provide a tool for recoveringthe lower portion of a broken drill string from a drill hole withoutfirst removing the portion of the drill string above the break.

ltis another object of this invention to provide a tool for recoveringthe lower portion of a broken drill string which enables the drillstring both above and below the break to be raised simultaneously.

These objects are obtained by a tool which comprises:

a. an upper body portion and a lower body portion in axial alignment;

b. a fluid chamber in said tool between said lower and said upper bodyportions;

c. each of said upper and lower body portions having a plurality oflongitudinal cavities spaced radially about the axis of the upper andlower body portions and communicating with the fluid chamber;

d. said longitudinal cavities being at acute angles to the axis of saidtool, the vertex of each of said angles being on the side of saidlongitudinal cavities nearest the fluid chamber, each of saidlongitudinal cavities having an opening at the end remote from saidfluid chamber, said opening defining a longitudinal groove along therespective body portion;

e. wedging members each having a crown of substantially uniform crosssection and a shank of bilaterally tapered cross section, one of saidbilateral sides having a substantially flat toothed surface;

f. a wedging member slidable in each of said longitudinal cavities withthe substantially flat toothed surface facing outwardly whereby thecrown of said wedging member is positioned in said longitudinal cavity,the shank of said wedging member projecting laterally and outwardly fromsaid body portion when the crown of said wedging member is slid awayfrom said longitudinal cavity;

g. a connector member secured to the upper end of said tool having meansfor connecting said tool to a drill rod;

h. fluid passages in said connector member, said upper body portion andsaid lower body portion communicating with said fluid chamber wherebyfluid from said drill rod may be delivered to said fluid chamber; and,

i. a driving tip secured at the lower end of said tool.

These objects are also obtained by a method which comprises:

a. lowering a hollow drill rod through the inner core of the drill pipe,said rod having a tool secured to its lower end consisting of an upperand a lower body portion in axial alignment, a fluid chamber in saidtool between said upper and said lower body portions each of said bodyportions having a plurality oflongitudinal cavities spaced radiallyabout the axis of the upper and lower body portions and communicatingwith the fluid chamber, said longitudinal cavities being at acute anglesto the axis of said tool, the vertex of each of said angles being on theside of said longitudinal cavities nearest the fluid chamber, each ofsaid longitudinal cavities having an opening at the end remote from saidfluid chamber, said opening defining a longitudinal groove along therespective body portion, wedging members each having a crown ofsubstantially uniform cross section and a shank of bilaterally taperedcross section, one of said bilateral sides having a substantially flattoothed surface, a wedging member slidable in each of said longitudinalcavities with the substantially flat toothed surface facing outwardlywhereby the crown of said wedging member is positioned in saidlongitudinal cavity, the shank of said wedging member projectinglaterally and outwardly from said body portion when the crown of saidwedging member is slid away from said longitudinal cavity, a connectormember secured: to and axially rotatable on the upper end of said toolcomprising a flange of cross section substantially equal to the crosssection of said upper body portion and means above said flange forconnecting said tool to the drill rod, a plurality of grooves on saidflange alignable with the openings of the longitudinal cavities in saidupper body portion when said connector member is axially rotated, fluidpassages in said connector member, said upper body portion and saidlower body portion communicating with said fluid chamber whereby fluidfrom saiddrill rod may be delivered to said fluid chamber, and a drivingtip secured at the lower end of said tool;

b. aligning the drill rod so that the upper body portion of said tool isin the inner core of the drill pipe above the break and the lower bodyportion is in the inner core of the drill pipe below the break;

c. discharging fluid through said hollow drill rod and said fluidpassages thereby projecting the wedging members in the longitudinalcavities of the lower body portion downwardly and outwardly from saidlower body portion and gripping the inner walls of the drill pipe belowthe break by means of the toothed surfaces of said wedging members;

d. rotating the drill rod and connector member of said tool so that thegrooves on the connector plate are aligned with the openings of thelongitudinal cavities in said upper body portion thereby permitting theshank portion of the wedging members in said longitudinal cavities topass therethrough and project upwardly and outwardly from said upperbody portion and gripping the inner wall of the drill pipe above thebreak by means of the toothed surfaces of said wedging members;

e. disengaging the hollow drill rod from said tool and raising the drillpipe above the break thereby raising the tool and the drill pipe belowthe break which is held by said tool.

In the drawings:

FIG. 1 is a perspective view of the apparatus of the present invention;

FIG. 2 is a perspective view of the upper portion of the apparatus withtwo sectional breaks shown for simplicity of illustration and a wedgingmember shown in exploded view;

FIG. 3 is a perspective view of another embodiment of a wedging membersuitable in the present apparatus;

FIG. 4 is a cross-sectional elevation of one embodiment of the apparatuswith one longitudinal cavity empty for purposes of illustration;

FIG. 5 is a broken section showing wedging member 9d in grippingposition against an inner wall of a drill pipe;

FIG. 6 is an illustration showing the apparatus positioned betweenbroken sections of pipe, and

FIG. 7 is a cross-sectional elevation of another embodiment of thepresent apparatus with a sectional break shown for simplicity ofillustration.

The tool shown generally at l in FIG. 1 comprises an upper body portion2 and a lower body portion 3 which are secured in axial alignment eitherby threaded connections or by welding into a single body unit. Aconnector member 4 is secured to and axially rotatable on the upper endof upper body portion 2. A hollow drill rod is shown in broken lines at5 to illustrate that tool 1 can be connected to such a drill rod bymeans of connector member 4 for the purpose which will become apparentfrom the description given below. A tapered member 6 is secured to thelower end of lower body portion 3 by a threaded connection or by weldingfor guiding the tool into the broken end of the drill pipe.

Upper body portion 2 has a plurality of longitudinal cavities 7 havingopenings which define longitudinal grooves 8 along upper body portion 2as can be seen with particular reference to FIG. 2. A wedging member 9is slidable in each of the longitudinal cavities 7 so that theirsubstantially flat toothed surface 10 is facing outwardly.

The wedging member 9 is shown particularly in the exploded view of thetool in FIG. 2 consists of a crown portion 11 of substantially uniformcross section and a shank portion 12 of bilaterally tapered crosssection. One of the bilateral sides has a substantially flat toothedsurface 10. By describing the shank as being bilaterally tapered theapplicant intends to show that the shank portion 12 is tapered along twosides. One tapered side should be substantially flat and have a toothedor notched surface. This is the surface that faces outwardly when thewedging member is positioned in longitudinal cavity 7. When the wedgingmember is projected in the manner to be described below thissubstantially flat surface 10 must provide a suitable wedging surface tosecurely grip the interior of a drill pipe. The other side of thetapered shank should preferably be rounded or contoured in such a manneras to match the contour of the longitudinal groove 8 so that the wedgingmember 9 can only be slidably positioned in cavity 7 with thesubstantially flat toothed surface 10 facing outwardly. While somedegree of tapering is permitted along the other two sides of the shankit must be appreciated that tapering along these sides to any extentreduces the surface area of surface 10 which is available for gripping.

In the embodiment shown in FIGS. 1 and 2 the substantially flat toothedsurface 10 of the wedging members are aligned with the outercircumference of body portions 2 and 3. This is desirable in a tool inwhich the diameters of the body portions are only slightly smaller thanthe inner diameter of the drill pipe. For example, a tool having upperand lower body portion each having an outer diameter of 3 inches can bepositioned in a pipe having an inner diameter of 3% inches and wedgingmembers 9 need only be projected slightly to provide the wedging andgripping action necessary.

In the case where the inner diameter of the drill pipe is considerablylarger than the outer diameter of the tool, a wedging member 9 as shownin FIG. 3 can be used. In this embodiment the shank portion 12 protrudeslaterally from the wedging member so that when crown portion 11 isslidably positioned in longitudinal cavity 7 the substantially flattoothed surface 10 will protrude from the side of the tool. When thewedging member is projected in the manner to be described below, thesurface 10 will wedge or grip the inner surface of the drill pipe. Forexample, wedging member 9 such as shown in FIG. 3 might be used in atool wherein the outside diameter of the upper and lower body portionsis 3 inches and the inner diameter of the pipe is 5 inches.

The crown portion 11 of the wedging members shown in FIGS. 2 and 3 havea sealing ring 13 for providing a substantially fluidtight seal whencrown portion 11 is positioned in longitudinal cavity 7.

In the embodiment of the connector member 4 shown in FIG. 2 said memberhas a flange 14 axially positioned on the upper end of upper bodyportion 2 and which is of a cross section substantially equal to thecross section of body portion 2. Flange 14 has a number of grooves 15equal to the number of longitudinal grooves 8 in upper body portion 2.These grooves are alignable with longitudinal grooves 8 by axiallyrotating connector member 4 so that wedging members 9 may project fromthe tool openings defined by longitudinal grooves 8. In the preferredembodiment of the applicant's tool, the wedging members 9 in upper bodyportion 2 cannot be projected from their position in longitudinalcavities 7 unless grooves 15 of plate 14 are aligned with longitudinalgrooves 8. The reason for this will become apparent from the descriptiongiven below with particular reference to FIG. 6. A connector means 16 ismounted above flange 14 for connecting the tool to a drill rod. In oneparticular embodiment of this invention the upper face of upper bodyportion 2 which abuts flange 14 of connector member 4 has a circulargroove (not shown) into which is inserted a pin (not shown) which isflush with the top of the upper face. The flange 14 has one or moreshear pins (not shown) in its lower end which are so positioned that thedrill rod 5 and connector member 4 can be rotated to the extent thatgrooves 15 are aligned with longitudinal grooves 8. When these groovesare aligned a shear pin on the flange 14 stops against the pin in theupper face and no further rotation in that direction is permitted.

One embodiment of tool 1 can be seen in the cross section shown in FIG.4. Upper body portion 2 and lower body portion 3 are threadedlyconnected in axial alignment. Longitudinal cavities 7a and 7b are shownin upper body portion 2 and longitudinal cavities 7c and 7d are shown inlower body portion 3. Cavity 7a is shown with the wedging member removedfor purposes of illustration. Cavity 7a has an opening at its upper endwhich defines a longitudinal groove 8a along the body portion 2. Groove8b similarly defines the opening of cavity 7b. A fluid chamber 17 islocated in upper body portion 2 and fluid passages 18a and 18b placecavities 7a and 7b respectively in fluid communication with chamber 17.It can be noted that longitudinal cavities 7a and 7b are each at anacute angle to the axis of the tool so that the vertex of each of theseangles is one the side of the longitudinal cavities nearest fluidchamber 17 so that a wedging member projecting from cavities 7a and 7bwould be projected upwardly and outwardly.

Connector member 4 is positioned at the upper end of upper body portion2 and the connector grooves 15 in connector plate 14 are shown alignedwith longitudinal grooves 8a and 8b. A connector means 16 is shown onconnector plate 14 for securing the tool to a hollow drill rod (notshown). A longitudinal fluid passage 19 in connector means 4 is alignedwith longitudinal fluid passage 20 in upper body portion 2 whereby fluidsuch as compressed air may be delivered from a hollow drill rodconnector to connector means 16 into fluid chamber 17. Fluid passages18a and 18b are in communication with fluid chamber 17 whereby the fluidmay be directed through the longitudinal cavities 7a and 7b.

Longitudinal passage 21 below fluid chamber 18 is aligned withlongitudinal passage 22 in lower body portion 3 when the bodies areaxially threaded whereby fluid overflow from fluid chamber 17 isdirected into fluid chamber 23 of lower body portion 3. Fluid passages18c and 18d are in communication with fluid chamber 23 whereby fluid maybe directed into longitudinal cavities 7c and 7d.

Wedging members 9 are positioned in each longitudinal cavity except 7awhere the wedging member was removed to show the longitudinal groovealong the tool body. It can be noted that the flat toothed surface 10 ofthe wedging member shanks are set in the longitudinal grooves 8 andaligned with the circumference of the body portion of the tool when theheat portions of the wedging members are positioned all the way incavities 7.

The section shown in FIG. 4 illustrates two longitudinal cavities andthis figure along with the other figures of drawings imply that foursuch cavities are spaced radially around each of the upper and lowerbody portions. While the preferred embodiments described in thisspecification show four such cavities, three cavities radially andequidistantly spaced apart in each of said body portions would functionwell. While less than two such cavities in each body portion wouldobviously not work, no significant gripping improvement was noted inembodiments utilizing more than four cavities radially aligned in eachbody portion. It can also be seen that cavities 7c and 7d are at acuteangles to the axis of the tool in the manner described for cavities 7aand 7bwith the vertex of their respective angles being on the side ofthe cavities nearest the fluid'chamber 23.

The operation of the tool will now be described with reference to FIGS.4 and 6. When a break occurs in a drill pipe during drilling operations,the breakis usually made known to the drill operator in a very shorttime due to the sudden drop in pressure of thefluid delivered to thedrill pipe or the sudden reduction in torque load. Sometimes the noiseoccasioned by the break can be heard as well.

When knowledge of a break occurs, drilling is stopped. The upper sectionof the drill pipe shown as 101 in FIG. 6 and located in earth formation103 is disconnected from the driving means and held by power tongs (notshown) or other gripping means on the drilling apparatus. By uppersection of drill pipe is meant that portion above break 102. At the timeof stoppage, the two sections of pipe will be separated by a distance ofa few inches depending on the alertness and reflexes of the operator. Ahollow drill rod 5 is lowered down the center of the upper section ofdrill pipe with a break locating device on its lower end. A breaklocating device which is suitable for this purpose and is well known inthe art consists generally of a cylindrical device threadedly secured atone end to the drill rod, the lower end of the device having hingedfingers kept apart by a spring that forces the fingers against the innerwall of the drill pipe. When the point of breakage is reached thefingers that had been bearing against the inner wall of the uppersection of drill pipe are forced into the break area and downwardprogress ceases when these fingers contact the top surface of the lowersection of broken drill stem.

When the location of the break is established its distance from the topof the drill hole can be measured by various means such as by markingthe top section of the hollow drill rod at a point which is aligned withthe top of the drill hole. The hollow drill rod is then raised and theapparatus of the present invention is secured on its lower end in placeof the break locating device. The hollow drill rod is again lowered intothe upper section of drill pipe to the point when the previously markedsection would indicate that the apparatus at the lower end of the rodwas located atthe break 102 with its upper body portion in the uppersection 101 of drill pipe and the lower body portion in its lowersection 104 of drill pipe. Since the recovery apparatus of thisinvention is generally longer than the conventional break locatingdevice, this difference must of course be taken into account in judgingthe distance to the break and locating the recovery apparatus atapproximately midpoint between the upper and lower sections of drillpipe.

It may be that the downward progress of the recovery apparatus isimpeded by material from earth formation 103 which caved into lowersection 104 of the drill pipe from the drill hole wall. For this reasonthe apparatus is equipped with a driving tip 6 so that the apparatus maybe driven through the obstructing material until the apparatus iscorrectly positioned between the upper and lower sections of the drillpipe.

Fluid from drill rod 5 is passed through longitudinal passage 19 inconnector member 4 shown in FIG. 4 and then into fluid chamber 17 vialongitudinal passage 20. Fluid is delivered into fluid passages 18 butwedging members are held in place by the edge of plate 14. Additionalfluid is delivered to fluid chamber 23 via longitudinal fluid passages21 and 22. Fluid from chamber 23 is delivered to longitudinal cavities 7in the lower body portion 3 via fluid passages 18. Fluid pressure forcesthe wedging members in the lower body portion to project downwardly andoutwardly from longitudinal grooves 8 in the lower body portion untilthe substantially flat toothed surface 10 of these wedging members gripthe interior wall of the lower section of drill pipe.

Whenthe wedging members of the lower body portion 3 are wedged in placein lower pipe section 104, the drill rod 5 is rotated until grooves 15on connector plate 14 are aligned with the longitudinal grooves 8 inupper body portion 2. As mentioned above, this alignment may be effectedwhen a shear pin in flange 14 abuts a pin located on the upper face ofthe upper body portion 2. When these grooves are aligned the fluidpressure in cavities 7 force wedging members 9 to project upwardly andoutwardly from longitudinal grooves 8 in upper body portion 2 until thesubstantially flat toothed surface 10 of these wedging members grip theinterior wall of the upper section of drill pipe 102. The sealing rings13 on the wedging members 9 insure a substantially fluidtight seal andmaintenance of fluid pressure.

When the wedging members of the upper and lower body portions are firmlywedged in place the delivery of fluid through'the hollow drill rod canbe stopped. The hollow drill rod is then rotated in the direction forunscrewing the rod from therecovery tool. With the wedging members inupper body portion protruding through grooves 15 in connector flange 14the connector member 4 is held firmly in place and does not rotate withthe drill rod. The hollow drill rod is disconnected and removed from thedrill pipe. The recovery tool is firmly secured in the upper and lowersections of the drill pipe thereby locking the two sections of drillpipe together. The upper section of drill pipe is raised by conventionalpipe recovery means.

When the upper section 101 is raised, the recovery tool and the lowersection 104 of the drill pipe is raised simultaneously. The lowersection of drill pipe 104 is pulled up with the upper section by meansof the firm grip of the upper and lower section by the wedging members.When the drill pipe is removed from the ground, the tool is easilyreleased from the drill pipe by knocking the pipe in the directiontowards the tool since the drill pipe is only held by the wedging actionof the wedging members.

The wedging action of wedging members 9 may be more clearly understoodwith reference to FIG. 5 wherein the iongitudinal cavity 7d of FIG. 4 isshown. In FIG. 5 the wedging member '9 is shown projecting from thelower body portion 3 and gripping the inner wall of the lower section104 of the drill o ipe. Thearrow in fluid passage 18d shows thedirection of fluid from chamber 23 which pushes wedging member 9 out ofcavity 7d to the extent whereby the substantially flat toothed surface10 of shank portion 12 comes in contact with the interior wall of thedrill pipe. The fluid is effectively sealed in by sealing ring 13 onhead portion 11. In FIG. 5 the wedging member projects downwardly andoutwardly to the extent generally used in normal operations of the tool,e.g., a tool body of 3-inch diameter in a drill pipe of 3% inch insidediameter.

It can be noted in FIG. 5 that the teeth on surface 10 are bevelled ltobit into the wall of the drill pipe when the tool is pulled upward. Forthe sake of convenience the preferred embodiment of the tool usesidentical wedging members in all of the longitudinal cavities. It can beappreciated that teeth bevelled in the manner shown in FIG. 5 will alsobe suitable for the wedging members in upper body portion 2 and will bitinto the wall of a drill pipe when the upper section of a broke drillpipesuch as item 101 shown in FIG. 6 is lifted.

The wedging members are slidably positioned in the longitudinal cavities7 before the tool is lowered down a drill pipe. It can be seen from thedrawings that these wedging members, particularly those in the lowerbody portion 3 can easily drop out of the tool since they are freelyslidable out of cavities 7. Of course the wedging members in upper bodyportion 2 may be held in cavities 7 by gravity but in the preferredembodiment are also held in place by flange 14 of connector member 4.When the tool is lowered down a drill pipe a wedging member in the lowerbody portion 3 may drop out to the extent that the toothed surfacecontacts the wall of the drill pipe. This does not restrict the movementof the tool down the drill pipe however since the surface 10 easilyslides over the drill pipe wall. When the lower body portion 3 of thetool is positioned in the lower section of the drill pipe as shown in104 of FIG. 6 the teeth of the wedging members grip the walls of thedrill pipe as an upward force is exerted on the tool. Even though thewedging members are otherwise free to slide out of cavities 7, theangles of the longitudinal cavities with respect to the tool body causesthe wedging members to project laterally and outwardly and the liftingforce is exerted on the tool thereby increasing the gripping force ofthe teeth against the drill pipe wall is increased.

FIG. 7 shows another embodiment of the tool of the present invention. Inthis embodiment the tool includes an upper body portion 202 and a lowerbody portion 203 in axial alignment and forming a tool body of unitaryconstruction. A connector member 204 is secured to and axially rotatableon the upper end of upper body portion 203 and is similar to connectormember 4 shown in FIGS. 1 to 6. A driving tip 206 is secured at thelower end of lower body portion 203 and is similar to driving tip 6 inthe previous figures of drawings. A wall section 205 secures the upperand lower body portions and defines a fluid chamber 207 therebetween.Wall section 207 is shown in broken section since the tool may be moreelongated that is shown in the drawings.

Upper and lower body portions 202 and 203 contain longitudinal cavities208 spaced radially around their respective body portions and positionedat acute angles to the axis of the tool. The vertex of each angle is onthe side of the longitudinal cavity nearest the fluid chamber. As in theembodiment shown in FIGS. 1 to 5, each of the longitudinal cavities havean opening defining a longitudinal groove along their respective bodyportion. Wedging members are not shown in FIG. 6 for simplicity ofillustration but is must be appreciated that the wedging membersdescribed previously are also suitable in this embodiment.

Each of the longitudinal cavities has a fluid passage 209 whereby thecavities are in fluid communication with fluid chamber 207. Longitudinalpassage 210 in upper body portion 202 is aligned with passage 211 inconnector means 204 whereby fluid from a hollow drill rod (not shown)connected to connector means 204 may be discharged into fluid chamber207 and then into the longitudinal cavities 208 via fluid passages 209.Wedging members in the longitudinal cavities are projected from thecavities by fluid pressure in the manner described in the previousembodiment.

I claim:

1. In combination with a drill pipe having upper and lower detachedsections, a tool for recovering embedded drill pipe detached from likedrill pipe extending from the top of the embedded pipe to a point aboveground by lifting said embedded drill pipe from the ground together withsaid like drill pipes, said tool comprising:

a. an upper body portion and a lower body portion in axial alignment;

b. a fluid chamber in said tool between said lower and said upper bodyportions;

. each of said upper and lower body portions having a plurality oflongitudinal cavities spaced radially about the axis of the upper andlower body portions and communicating with the fluid chamber;

d. said longitudinal cavities being at acute angles to the axis of saidtool, the vertex of each of said angles being on the side of saidlongitudinal cavities nearest the fluid chamber, each of saidlongitudinal cavities having an opening at the end remote from saidfluid chamber, said opening defining a longitudinal groove along therespective body portion;

e. wedging members each having a crown of substantially uniform crosssection and a shank of bilaterally tapered cross section, one of saidbilateral sides having a substantially flat toothed surface wherein saidteeth are inclined in the direction of said crown;

f. one of said wedging members slidable in each of said longitudinalcavities with the substantially flat toothed surface facing outwardlywhereby the crown of said wedging member is positioned in saidlongitudinal cavity, theshank of said wedging member projectinglaterally and outwardly from said body portion when the crown of saidwedging member is slid away from said longitudinal cavig. a connectormember secured to the upper end of said tool having means connectingsaid tool to a drill rod for raising and lowering said tool;

h. fluid passages in said connector member communicating with said fluidchamber, the longitudinal cavities of said upper and lower body portionscommunicating with said fluid chamber whereby suflicient fluid from saiddrill rod may be delivered to said longitudinal cavities to project thewedging members therefrom; and

said upper body portion into gripping engagement with said upperdetached pipe section and from said lower body portion into grippingengagement with said lower detached pipe section, said upper and lowerdetached pipe sections extending respectively axially upward anddownward from said fluid chamber so that both said upper and lowerdetached pipe sections are simultaneously axially moved upon axialmovement of said drill rod.

j. a driving tip secured at the lower end of said tool.

2. In combination with a drill pipe having upper and lower detachedsections, a tool for recovering embedded drill pipe detached from likedrill pipe extending from the top of the embedded pipe to a point aboveground by lifting said embedded drill pipe from the ground together withsaid like drill pipe, said tool comprising:

a. an upper body portion and a lower body portion in axial alignment;

b. a fluid chamber in each of said upper body portions and lower bodyportions;

c. the upper body portion having a plurality of longitudinal cavitiesspaced radially about its axis and communicating with the fluid chamberin said upper body portion;

d. the lower body portion having a plurality of longitudinal cavitiesspaced radially about its axis and communicating with the fluid chamberin said lower body portion;

. each of the longitudinal cavities of the upper body portion and thelower body portion being at an acute angle to the axis of said tool, thevertex of each of said angles being on the side of said longitudinalcavity nearest the fluid chamber, each of said longitudinal cavitieshaving an opening at the end remote from the fluid chambers, saidopening defining a longitudinal groove along the respective bodyportion;

. wedging members each having a crown of substantially uniform crosssection and a shank of bilaterally tapered cross section, one of saidbilateral sides having a substantially flat toothed surface wherein saidteeth are inclined in the direction of said crown;

g. one of said wedging members slidable on each of said longitudinalcavities with the substantially flat toothed surface facing outwardlywhereby the crown of said wedging member is positioned in saidlongitudinal cavity, the shank of said wedging member projectinglaterally and outwardly from said body portion when the crown of saidwedging member is slid away from said longitudinal cavi- W;

h. a connector member secured to and axially rotatable on the upper endof said tool and comprising a plate of cross section substantially equalto the cross section of said upper body portion and means above saidplate connecting said tool to a drill rod for raising and lowering saidtool, a plurality of grooves on said plate alignable with the openingsof the longitudinal cavities in said upper body portion when saidconnector member is axially rotated to permit passage therethrough ofthe shanks of the wedging members in said upper body portion;

. said wedging members extending simultaneously from i. fluid passagesin said connector member communicating with the fluid chamber of each ofsaid upper and said lower body portions, the longitudinal cavities ofeach of said upper and said lower body portions communicating with thefluid chamber of their respective body portion whereby sufficient fluidfrom said drill rod may be delivered to said longitudinal cavities toproject the wedging members therefrom;

j. said wedging members extending simultaneously from which are alignedwith the openings of the longitudinal cavities in the lower body portionto permit passage therethrough of the shanks of the wedging members insaid lower body portion.

3. A tool as claimed in claim 1 wherein said driving tip is tapered andhas grooves positioned around said tapered bit which are aligned withthe openings of the longitudinal cavities in the lower body portion topermit passage therethrough of the shanks of the wedging members in saidlower body portron.

4. A tool as claimed in claim I wherein the connector member is axiallyrotatable on the upper end of said tool and comprises a plate on saidupper body portion and means above said plate for connecting said toolto a drill rod, a plurality of grooves on said plate alignable with theopenings of the longitudinal cavities in said upper body portion whensaid connector member is axially rotated to permit passage therethroughof the shanks of the wedging members in said upper body portion.

1. In combination with a drill pipe having upper and lower detachedsections, a tool for recovering embedded drill pipe detached from likedrill pipe extending from the top of the embedded pipe to a point aboveground by lifting said embedded drill pipe from the ground together withsaid like drill pipes, said tool comprising: a. an upper body portionand a lower body portion in axial alignment; b. a fluid chamber in saidtool between said lower and said upper body portions; c. each of saidupper and lower body portions having a plurality of longitudinalcavities spaced radially about the axis of the upper and lower bodyportions and communicating with the fluid chamber; d. said longitudinalcavities being at acute angles to the axis of said tool, the vertex ofeach of said angles being on the side of said longitudinal cavitiesnearest the fluid chamber, each of said longitudinal cavities having anopening at the end remote from said fluid chamber, said opening defininga longitudinal groove along the respective body portion; e. wedgingmembers each having a crown of substantially uniform cross section and ashank of bilaterally tapered cross section, one of said bilateral sideshaving a substantially flat toothed surface wherein said teeth areinclined in the direction of said crown; f. one of said wedging membersslidable in each of said longitudinal cavities with the substantiallyflat toothed surface facinG outwardly whereby the crown of said wedgingmember is positioned in said longitudinal cavity, the shank of saidwedging member projecting laterally and outwardly from said body portionwhen the crown of said wedging member is slid away from saidlongitudinal cavity; g. a connector member secured to the upper end ofsaid tool having means connecting said tool to a drill rod for raisingand lowering said tool; h. fluid passages in said connector membercommunicating with said fluid chamber, the longitudinal cavities of saidupper and lower body portions communicating with said fluid chamberwhereby sufficient fluid from said drill rod may be delivered to saidlongitudinal cavities to project the wedging members therefrom; and i.said wedging members extending simultaneously from said upper bodyportion into gripping engagement with said upper detached pipe sectionand from said lower body portion into gripping engagement with saidlower detached pipe section, said upper and lower detached pipe sectionsextending respectively axially upward and downward from said fluidchamber so that both said upper and lower detached pipe sections aresimultaneously axially moved upon axial movement of said drill rod. j. adriving tip secured at the lower end of said tool.
 2. In combinationwith a drill pipe having upper and lower detached sections, a tool forrecovering embedded drill pipe detached from like drill pipe extendingfrom the top of the embedded pipe to a point above ground by liftingsaid embedded drill pipe from the ground together with said like drillpipe, said tool comprising: a. an upper body portion and a lower bodyportion in axial alignment; b. a fluid chamber in each of said upperbody portions and lower body portions; c. the upper body portion havinga plurality of longitudinal cavities spaced radially about its axis andcommunicating with the fluid chamber in said upper body portion; d. thelower body portion having a plurality of longitudinal cavities spacedradially about its axis and communicating with the fluid chamber in saidlower body portion; e. each of the longitudinal cavities of the upperbody portion and the lower body portion being at an acute angle to theaxis of said tool, the vertex of each of said angles being on the sideof said longitudinal cavity nearest the fluid chamber, each of saidlongitudinal cavities having an opening at the end remote from the fluidchambers, said opening defining a longitudinal groove along therespective body portion; f. wedging members each having a crown ofsubstantially uniform cross section and a shank of bilaterally taperedcross section, one of said bilateral sides having a substantially flattoothed surface wherein said teeth are inclined in the direction of saidcrown; g. one of said wedging members slidable on each of saidlongitudinal cavities with the substantially flat toothed surface facingoutwardly whereby the crown of said wedging member is positioned in saidlongitudinal cavity, the shank of said wedging member projectinglaterally and outwardly from said body portion when the crown of saidwedging member is slid away from said longitudinal cavity; h. aconnector member secured to and axially rotatable on the upper end ofsaid tool and comprising a plate of cross section substantially equal tothe cross section of said upper body portion and means above said plateconnecting said tool to a drill rod for raising and lowering said tool,a plurality of grooves on said plate alignable with the openings of thelongitudinal cavities in said upper body portion when said connectormember is axially rotated to permit passage therethrough of the shanksof the wedging members in said upper body portion; i. fluid passages insaid connector member communicating with the fluid chamber of each ofsaid upper and said lower body portions, the longitudinal cavities ofeach of said upper and said lower body portions communicating with thefluid chamber of their Respective body portion whereby sufficient fluidfrom said drill rod may be delivered to said longitudinal cavities toproject the wedging members therefrom; j. said wedging members extendingsimultaneously from said upper body portion into gripping engagementwith said upper detached pipe section and from said lower body portioninto gripping engagement with said lower detached pipe section, saidupper and lower detached pipe sections extending respectively axiallyupward and downward from said fluid chamber so that both said upper andlower detached pipe sections are simultaneously axially moved upon axialmovement of said drill rod; and k. a tapered member at the lower end ofsaid tool having a plurality of grooves positioned around said memberand which are aligned with the openings of the longitudinal cavities inthe lower body portion to permit passage therethrough of the shanks ofthe wedging members in said lower body portion.
 3. A tool as claimed inclaim 1 wherein said driving tip is tapered and has grooves positionedaround said tapered bit which are aligned with the openings of thelongitudinal cavities in the lower body portion to permit passagetherethrough of the shanks of the wedging members in said lower bodyportion.
 4. A tool as claimed in claim 1 wherein the connector member isaxially rotatable on the upper end of said tool and comprises a plate onsaid upper body portion and means above said plate for connecting saidtool to a drill rod, a plurality of grooves on said plate alignable withthe openings of the longitudinal cavities in said upper body portionwhen said connector member is axially rotated to permit passagetherethrough of the shanks of the wedging members in said upper bodyportion.